Process and apparatus for the vapor phase production of ammonium nitrate



UM NITRATE I Jeparaor /esse/ H. A, BEEKHUIS, JR

r Filed May 7'; 195o fer/apar ug. 20, i935.

PROCESS AND APPARATUS FOR THE VAPOR PHASE PRODUCTION OF' AMMONI HERNAN ALBERT BEE/mul BY Z ATTQRNEY H. A. BEEKHUIS, JR

PROCESS AND APPARATUS FOR THE VAPOR PHASE PRODUCTION OF AMMONI UM NITRATE Filed May '7, 1930 2 Sheets-Sheet 2 l Patented Aug. 20, i935 Z,0ii,74

PROCESS AND APPARATUS Foa THE VA ron PHASE ritonUCTroN F AMMoNIUM NITRATE Herman Albert Beekhuis, Jr., Syracuse, N. Y., Y assigner to Atmospheric Nitrogen Corporation,

New York, N. Y., a corporation of New York Application May 7, 1930, Serial N0. 450,459 l 47 Claims.

This invention relates to a process for the production of ammonium nitrate. More particu- Aiarly, this invention relates toa process for the production of ammonium nitrate by reaction of 5 ammonia, nitrogentetroxide, water vapor and oxygen, whereby a solid ammonium nitrate product is directly obtained. Y Y a I-t has heretofore been proposed to produce n ammonium nitrate by reaction of nitrogen 10 tetroxide (by which term is meant nitrogen oxide correspondingto the` formula NO2 or N204 or a mixture of NO2 and NzOrin any proportions), water vapor, and oxygen with ammonia. In carrying out the process as previously proposed,

15 a gas containing nitrogen tetroxide, 'oxygen and water vapor in desired proportions is mixed with :a quantity of ammonia insuiiicient to react with the whole of the nitrogen tetroxide in accordance Ywith the equation,

The solid ammonium nitrate thus y:formed is removed from Ythe residual gases in which it is suspended, and a further quantity of ammonia added 25 to react with the nitrogen tetroxide, water vapor and oxygen of theV residual gases. By making Vseveral additions of ammonia to the original nitrogen tetroxide gas with intermediate removal i of ammonium nitrate, the amount of nitrogen 3() tetroxide remaining is too small to be suitable for further treatment. y

" Numerous diniculties are encountered in carrying out the process as described. The equation given above'for the production of ammonium Y, 35` nitrate represents butV one of several reactions which'may take place simultaneously upon admixing 'ammonia with the nitrogen tetroxide, Water-vapor and oxygen. The nitrogen tetroxide gas as commercially prepared contains a quantity 40 of nitric oxide (NO). In treating such va gas with ammonia, nitrogen and water are formed by `an oxidation of the ammonia by means of the Vnitrogen oxides. vThis oxidationreaction may be expressed by the equation, l

' reactions which take place.

with ammonium nitrite and the decomposition of the nely divided ammonium nitrate by reason of high temperatures generated by the chemical It is an object of the present invention to pro- 5 vide an economic process for the direct production of ammonium nitrate by which xed nitrogen in the form of nitrogen oxides and ammonia iseniciently transformed into ammonium nitrate. Itis further, amongthe objects of this invention to so modify and change the several steps of prior processes for the direct production of ammonium nitrate as to result in marked improvementV in the operation ofhsuch processes; to provide new conditions for carrying out the several steps of those processes; and to so correlate those steps and the conditions under which they are operated as to provide a new and economic process for the direct production of ammonium nitrate. Other objects ofthe invention Will in part 2 0 be obvious and will in part appear hereinafter,

I have discovered that ammonium nitrate may be directly produced by the interaction inthe gaseous phase of ammonia with nitrogen tetroxide, oxygen and water vapor in an eificient` and economic manner, and with reduced losses of iixed` nitrogen. This I `have accomplished by an improved coordination and correlation of the manner of introducing and admixing the Vammonia with the other components; the quantities 'of ammonia and water vapor utilized, and the temperature at which the reaction takes place. (It is to be understood that throughout the speciiication and claims, when a quantity of gas is mentionedreference is made to an amount of the gas by volume). Thus the ammonia'is introduced into a gas containing the nitrogen tetroxide, oxygen and water vapor and rapidly Aadmixed therewith by means of a specially devised mixing apparatus; they amount of ammoniais 40 less than about 0.3 times that required to neutralize all the nitrogen tetroxide; the amount of water vapor is at least one part to each one part of ammonia, and the temperature of the reaction is maintained within the range of below about 125 C. and above the dew point of water vapor in the gas mixture. Y l

I havev found that numerous factors influence the eiiciency of the reaction between ammonia, nitrogentetroxide, water vapor, and oxygen to formammonia and that the commercial success of a process employing that reaction is largely determined by a propercontrol of the conditions under which the reaction is carried out. Without in any way limiting my invention thereto, but

' being 'dependent lilon temperature and vconcen-V tration 'of nitrogen `tetrf'nide Vand water vapor. l Accordingly/,1'whileEquation IV'would appearvto Y f' indicate that-about'50% of the nitrogen tetroxide the eiiiciencyof the reaction' ofkvarious conditions of operation as hereinaiter'setforth; I havev found thatthe data obtained for the reactions takingY sults in the loss oi nxed" 'nitrogen'.`r` Equation IIV ,Y represents `a'reversible reaction, the equilibrium conditions vwith Vrespect "t I 'the ratio na gas may heeiicientlyl utilized by lthe addition t iin the gas .wouldbe combinedwith water vapor"y 3'0,V as HzNzOs andjvhenceflin*condition for reactionW Worf* ammonia', not all.y of 'the' nitrogen tetroxide 1 with ammonia. VF/ithincrease intemperaturea smaller proportion'. off nitrogen tetroXidel would l vbefin 'thev form .of vI-zNzOaand' hence a 'smaller proportion of ammonia 'may Aefoiently;react with 'thegas eWithV a relatively dilute NOzjgas the l proportion of HfiNzOsis .also decreased.` 4 Y .Y I have found that in mixing ammonia witha Y Y9% lNOz'gas containing,4.2% watervapor'ata temperature'ofabout 50 C., the eiciencyzof the {reaction rapidly'decreasedwhen they ammoniaY v 4 A quantity'more I than about 0.3,` times'the amount of nitrogen tetroXide contained.v

was added in .a

in-Vlthe gas. On Vthelother hand;v 'l1r hayeffound Y"that-Vin mixing lammoniak with/largas containing about `6,11% or less of nitrogen tetroxiderit is lad-Y less than about 0.25 times'. the amountrequiredto wneutralizeall the-.nitrogen tetroxide contained in` n thegas.

ide,- waterv vapor and.` oxygen, `liberates a vcon- Siderable amount of KVheat which," by elevatingthe A by: the" intr'oductioniof a limited amount of arntemperaturey of the reacting gases, deleteriously `iniiuencesthe efliciency of the reaction. `Ihave Yfound thatthe reaction mixture shouldbe maintained at a temperature below about '125- C. inf order to prevent an excessive loss of xednitroe" gen; I v'have found furthen' thatlit. is preferable vv'to control the temperature by introducing vthe Y ammoniaV into a gas contaningnritrogen tetroxide at a temperature sufcientlypbelowlZ? C. that monia insucient heat' is'liberated 'by lthe 4reaction to' elevate the temperature of.: the reactionA mixture abovegabout v12,5" C.ff,l 3y,.tlf1'V i correlating ,the ftemperatureY of the 4nitrogen?f-tetroxide gas and Ythe amount of ammonia` added thereto even alocal excessive' heating of the reactionJIniXture is preventedfltis-fpossible, howeverto obtainl satisfactory resultsglby providing highlyeiicientr vmeans for "removing thefheat of f the reaction;

y 'Whenla vnitrogen"tetroxidegas ,at an elevatedv temperature'is to bepemployed in the production of! ammonium nitrate. in `vaccordance .withmy in-j v-Ventionggthe preferred method of controlling the4 as a possible'explanation for' the influence upon`r isable that the .amount of` ammonia added v.he

K rEhe reaction of ammonia with nitrogen tetroX- ybut exercises a deleterious infini-:nce upon. j'r'eaetion to forni ammoniumi'iitratebV .Qf found that itis preferahle'to adinix a zoncentratedv ammonia gas with the' nitrogenlftetronide gas, .'vavoiding thereltjyfanr unnecessary dilution `oi they reactionmixture "of gases, Vs/hile excess of f 2,011,704y Y temperature 'ofy the reactionmixture entails cooling the nitrogentetroxide gas prior to the vinytroduction thereton of a limited `lquantity of ammonia.

An association .of the nitrogen tetroxide and prior to its reaction with am'rnoniav would seem to be necessary for high eiiciency of rthe reaction f to yform ammonium nitrate., Thenitrogen tetroX- ide gas, prior to introductionkof vammonia therey. to, should contain aquantity of water vapor at least equal tothe amount of ammonia'introduced thereto: Ihave found that it is preferable for economic operation of the processrto regulate the amount of water'vapor with relation tothe nitrogentetroxide content of the gas and that a-suitable proportion is'between 0.5 andv 2.5 or more parts ofV watervapor to every 1 partY of NO2,

l butin no case should therebe a sufficient amount` to form a liquid condensate'in the gas withwhich Vthe ammonia is -rn'ixed' l't1 isv apparent, there- Vwater Vapor as indicated by vEquation II-above, l

foregfthat 'the'r amount [of excessy water vaporY whichY may/bez employed is dependentupon the temperature of operation, andthe gases,V prior 'tothe introductionvof ammonia,` should be at a temperatureabovefthe dew point'7 ofthe water .liquid condensate occurs,v corrosion ofthe apparatus in which the gas is treated-results. Furthermore, I have found that the presence of such a condensate in thefgases into which ammonia is'.v introduced results in anjundesirable moisture content of the ammonium nitrate i product',Y and what is still more serious, results-finl a contamination ofthe lprccluctfwith ammonium nitrite and other impurities. l

vapor contained therein. IfV the formation Yof a *I have further Vdiscovered that k'the concentrar tion-sof the nitrogen Yte'troxi'de in the reaction mixtureof gases plays an important role inthe efciency lof VYthe reactionto form ammonium nitrate. Equation II'above may serve toeXpIain thisk discovery.A "As hasalready been stated, the

YVlresultsobtained by this invention indicate'vthat the-reaction between nitrogenY tetroxide, water vlvapor, oxygen, andarnn'ionia takes yplaceV in two .stagesy rstg'thewforrnation: Yof the compound HzNgOs and the reactionof arnmoniagwith this product. The formationof HzNzOswould'appear to; occur as the result Yor" the reversible reaction represented by Equation II- abover andthe amount This interpretation or" the chernistrylof the'process lserves to ,explain irnyA discovery that thenitrogen highly 'diluted' in thegaseous lreaction mixture since van excessive?dilution not only requires the treatment of unnecessarily large amounts ci gas the I rhave Y of H2N2O5 present in a mixture ot gasesinay be o. represented by the equilibrium- 'equation for this 'tetroxide and water' vapor should' not lbe tooY oXygcn'o-Ver the Vamount"required vfor theA reaction to form :an'mioniunV nitrate shouldj `be present,fanyundulylargeexcess is to be avoided because of the -dilutionoic thenitrogentetroxide thereby. I have found itpreferable@therefore,`

tto-limit rthe amount of oxygenin lthe reaction rmixture to an amount/:not greaterith'an about l0 :of the total volume of the gas with which the for `their erlicient conversion into ammonium nitrate. The desirability of rapid mixing is indicated by a comparison of Equations III' and IV above.` The reactions represented by these equations take'place with great rapidity so that if in the'mixturey oi gases there be la localized excess of ammonia, the `reaction of Equation III result- Y ing-in a loss of fixed nitrogen takes place where the excess ofarnmonia exists even ior'avery short period of time.

' Y! Furthermore, I have found that it is important that the ammonia should be introducedv into a gas containing nitrogen tetroxide, water vapor i and oxygen, and that the nitrogenoxides should beY relatively completely .oxidized to nitrogen tetroxide prior to the introduction' of ammonia,

' for examplerthe state o oxidation of the nitrogen oxide 4gasis preferably such that 80% or more ofq'the nitrogen oxides are present as NO2.

Ylilly invention-accordingly comprises the several steps and the relation ofone or more of such steps with respect to each of theothers and the apparatus embodying features of construction, combinations oi elements and arrangement of parts which are adapted to eiect such steps., all as exemplified in the following detailed disclosure, and the scope oi the invention will be indicated in the claims.

For a` fuller understanding of the nature and objects of my invention, reference should be 'had to `the following detailed description taken in connection with the accompanying drawings, in which:

, Fig. 1 is a diagrammaticrepresentation of the process of this invention as carried outY in one type 'of apparatus; Y f

Fig. 2*is an elevation, in cross-section, of the reaction vessels oi Fig. l; and

Fig. 3 is a diagrammatic representation of the process of this invention as carried out in a difvferent type of apparatus from that illustrated in'Fig. 1. i

Y Referring` now to Fig. l, a Vnitrogen oxide gas such as is obtained from the heat exchangers and coolers of an ammonia oxidation system, which contains oxygen anda relatively large amount otwater vapor, is passed through a pipe `l into an oxidation chamber 2 where the nitrogen oxides are oxidized to nitrogen tetroxide, and the resulting gas containing nitrogen tetroxide, water Vvapor and oxygen, leaves chamber' 2 through a pipe'3. It is apparentthat a nitrogen oxide gas from a source other than an ammonia oxidation system, may bepassed into chamber 2 forv treatment therein, or`if a gas of the proper composition is available, the treatment in chamber 2 may be omitted and the gas passeddirectly through pipe 3 for use as hereinafter described. The gas Vpassed through pipe 3 preferably contains about Vthe gas passed into chamber 2 contains insufficient oxygen for the oxidation of the nitrogen oxides, additional oxygen may be admixed therewith prior to their passage into chamber 'if and ii f required to make up -for any deficiency. in the amount of .free oxygen with respect to the desired proportion ,of oxygen and nitrogen tetroxide, oxygen mayfbe added to the gases passing through pipe 3.

From pipe 3 the gases are passed into the bottom of a gas cooler i wherein they mingle with residual gas from a pipe 2S and are intimately contacted with an aqueous medium having a pree determined composition and temperature, preferably a solution of nitric acid, introduced into the top of the cooler from a pipe 6. `Cooler i preferably contains va packing material which ensures intimate Contact between the gases passed `through the cooler and the nitric acid solution introduced therein. The nitric acid after con-- tacting with the gas is withdrawn from thevbottom of cooler l through a pipe 5, and is circulated through a cooler l in indirect contact with a cooling medium such as water, back to the top of cooler li for renewed contact with gas from pipe 3. "Ihe cooling water is introduced into cooler 'I from a pipe and withdrawn therefrom through a pipe 9. By its contact in cooler d with cool dilute nitric acid, the gas Afrom pipe 3 is cooled to a desired temperature and its water Vapor content is adjusted either by taking up from the nitric acid a quantity of water corresponding to saturation ci the gas under the conditions of temperature and concentration of the acid, or ir" the gas from pipe 3 contains an excess of water vapor above that corresponding .to saturation in contact with the nitric acid in cooler the excess water vapor condenses out of the gas. The nitric acid solution likewise may absorb nitrogen oxides from the gas which react to form nitric Y acid and in such a casein order to maintain a` be accomplished in other manners than that de-V scribed, for example by passing the gas in indirect heat exchange with a cooling medium. By employing direct cooling with aqueous nitric acid, however, simultaneously with the cooling of the gas its waterl vapor content is adjusted by controlling'the concentration of the acid and the temperature of cooling. Furthermore, I have discovered that an'acid of proper concentration does not remove from a gas 'contacted therewith finely divided particles of solid ammonium nitrate. The residual gas introduced intoA cooler 4 carries with it a small amount of suspended solid ammonium nitrate. This ammonium nitrate not only does not interfere with the cooling of the gases, as it would in case the heat transfer were through metal surfaces upon which the ammonium nitrate would deposit, but also the ammonium nitrate in large part passes with the gases through the cooler and may be recovered along with additional ammonium nitrate subsequently formed and recovered as described below.

The gas passed through cooler l is withdrawn through a pipe l and passed to a, reaction vessel I i where itis admixed with ammonia from a pipe i2. The amount of ammonia vintroduced into reaction vessel i i is proportioned with respect to the amount of nitrogen tetroxide introduced thereto such that the amount of ammonia in the reaction mixture of gases is less than about 0,3 times, and for example, employing a gas containing between 5 and 6% or" nitrogen tetroxide, is preferably between about 0.10 and 0.25 times the amount required to neutralize all of the nitrogen tetroxide. The ammonia, nitrogen tetroxide, oxygen and water Vapor react to form ammonium nitrate `vvhichis ,suspended as a finelyl divided 1' solid inthe gases leavingreaction vessel Hl.: As

a* result 'of Ythis reactiongto form ammonium rmtrate,V considerable lquantities. Vof heat .arevf'liber- 'ated'.u AThe temperatureV attained bythe reacting gases asia result of this liberation ofheatshould be limited to,aftemperatureflmelovv'aloout 125;"v C. Y

As 'notedfabovav the 'temperature of they reacting course of .t 1e

4by the reaction to yraise the ,temperature of the ever, that the nitrogen tetroxidegas belnotcooled in gas coo'ier l to sucha lowltemperature that the Watervapor content, which is limitedrfby the tem- I perature of thegas, Wouldfbeless thanabout- 1 .i part of Water vapor for every konefpart'ofy ammonia subsequently added thereto. :It has.` been foundthat a;V process maybe rs'atisfactorily oper- K ated when a containing not more than about 65% nitrogentetroxide in passing throughy gas cooler, iis cooled to. a temperature of about 406 C. and the reactinggases .in reactionf vessel H are l maintained l throughout ther coursel of the y,re-

action at temperatures between about l0? C. and 125 C. Undersuch conditions, by employingin gascooler'd an aqueous solution yof nitric acid containing :about 50 %VY HNOa at aboutv 40 'C.,the

1 nitrogen tetroxidegas may be cooled ftofa-nrappropriateternperature and its waterrvapor'fconv tent automatically regulatedA either bythe gas taking up.y the proper ramount of," moisture from the acid orgiving upto theaeid'any undesirabie excessof Water vapor Whichgit may. contain. If any aqueous medium other than arnitricacidsolution isemployed inthe cooling of the gas, it is apparent thatthe moisturel content of the gasv Vmay likewise be regulated by controlling the Ytemperature V'and concentration of* such A@aqueous medium. l

Itis of importancethat theammonia be introducedyin reaction vesself! i, into the nitrogen tetroxide gas containingfoxygen and Watervapor g and be quickly and thoroughly admix'edWithtl'nsV gas. VIn Fig. 2 isshownone type ofgreaction'vessel which has been found toY be suitable/forlcarryingV` Y out the reaction.v In, thatvfigure, the numeral E3 Y, designates a cas'ingprovided'with closur'esli and l5,whichtogether, define a mixing and reaction chamber l5.` A ypipe lf'lrwhich corresponds to Clt (it)y .oppositehendof casing llapipe 25 which opens Y' tained therein or' otherwise disposed of.

pipe l 'of Figgfl, opens through closure v55 into f chamberl and serves for the introduction into chamberldof'the nitrogen tetroxide; oxygen and Water'vaporgas. A secondpipe i8 lserving furthe introduction of ammonia into'chamber It,

.passes through closure l5 andterminatesin are--v stricted oriceformed inaplate i9 seated on'the endrof pipe ,I8 Withinchamber I6.r Adjacent the througheasing I3'into1chamber l5 Yis provided for removing thefunreacted .gasesjand the reaction products from chambery! 6, A rotatable shaft l2l has one endl seatedin a bearing 22 carried by closure l5 and extends through closure M byway ofrargas-tightioint to afpoint Without the 'reacf tion vessel; Means not shown in Fig.' 2.are provided for rapidly rotating shz'iftli.y Shaftf?! within reaction chamber lcarries av grid 23 which2 isV attachedto theshaft for rotation therewith.

By rapidly` rotating shaft 2! andl grid 23; ajturhulence is AI nechanically.impartedto the stream induced by a fan 25.

of nitrogen tetrozide gas, vpassing through reaction chamberl i6. The ammonia is introduced as a restricted stream flowing through the orifice in plate 9S into the' turbulentlyl flowing stream of nitrogenitetroxide gas, rand isy rapidly and thoroughlyfadmixed; Withv Vthe nitrogen tetroxide,

4roxygen' and Water Vapor, with Which'it reactsto form rammonium;nitrate:

l lReferringincvv to Fig. 1, the gases leaving Vre# action vessel ll carry with them the'ammonium nitrateproo'lucedv therein and pass through a pipe nitrateisseparated Vfrom the gas stream and re-` l movedthrough a pipe 26. Separator 25 may be of v Y, rany desired type such as ra centrifugal, lbaile or electrostaticseparatori The Vgases from which the ammonium' nitrate has been in 'large part re' action with ammonia in reaction vessel t i to form additional-quantities of vammonium nitrate.r The Y recirculation of the ,'gasesfrom separator V 25' is VA portion ofthe residual gas containing nitrogen tetrcxi'degoxygen and Water vapor from separator 25 passing through pipes 2 and28 ris bledV fromV 'Y thecirculatory system above ydescribed and passed through 'ai pipe to a second circulatory system wherein.ammoniumnitrate is rproduced there- `Vfrom inamanncr similarftozthetreatment of the v 'nitrogen tetroxide oxygen andgwaterV Vapor gasV from pipe' 3. g Thisseoond circulatory systemrcomprises aifgas coolerl 39,'1cooler Sllfreaction Vessels and to anda separator 4l, which may beof the sanieitype as the: corresponding portions of the ,circulatoryYsystemA above described. In gas .cooler 3l the gas from pipe .tlis cooled and itsY Water vapor. content: adjusted by direct contact with dilute nitric acidpassed into cooler 3i from a pipe 32'. After contactewith thegas the nitricl acid is Withdrawnvfrom cooler Sifthrough a pipe 1 33, passed through a cooler, Where it is cooledV by means of cooling Water, andisrecirculated toV cooler v3i through pipe32. As inthe ease of the gas iii-cooler@1 it is preferred Ato'cool the gas'inA ,coolerfl to a, temperaturev ofab'out 40C; The

thus cooledrgas is passed by Way ofV pipes-35,3, 37 and 38' through reaction vessels Vsgjand' 45, Whereinrthey are treated with ammonia to produce ammonium nitrater and thence to separator Mwhere the ammonium nitrate is removed trom the residualc unreactedf gas. As yshoum in the drawings, the'gas from Yreaction vessel 39 passes vthrough af rest chamber` f32before entering reactiongvessel 4Q. Fromseparator el the ammonium nitrate produced inereaction Vessels 39 and il? is removed through a pipeV t3 and residualv gas :re-V turned throughi'pipes lli and45 to cooler Bimby means of a fank 4E'. A'portion of the VgasV is discharged from theV system through a'pipe 4'! and' may 'if desired. `be treated to recover the'residual relativelyvsmall amount' of 'nitrogenoxdes con- -The heat liberated byv thegforrnation ofv ammoniumy nitrate in reaction vessels 353 and Ai!) is removedlfromthe gas by dissipation during passage from thesevessels to gas cooler 3i and in gas cooler 3| by contact With'cooled dilute nitric acid. Thecontentl of water Vapor, 'nitrogen tetroxide vandioxygen of the residualgasis adyttl-to a separator 25 wherein the solid ammonium y i justed .in.- coole"ry 3l by direct contactofdilute nitric acidvl therewith andby kadmixture with the gas from jpipe 3.9. The thus treated gas inreaction Vessel 39 is'mixedr in reaction vessels 39 and is with ammonia, frompip'e's .as and 49 lrespectively. In each reaction vesselan amount of,

series is advantageous when the nitrogen tetroxp ide concentration in the gas is low, for example about 2% NO2. In such case the temperature o1 the gases leaving `reaction vessel 39 is suiiiciently low `that a further quantity oi ammonia may be added in reaction vessel 40 and a temperature of 125 C. not exceeded. Thus, there may beV introduced into vessel 3e an amount of ammonia about .25 Vtimes the amount required to neu- `tralize all of the nitrogenA tetroxide passed into the vessel and a like amount of ammonia maybe lintroduced into vessel 40., Intermediate the two reaction vessels 39 and @.0 the gas'containing ammonium nitrate formed in reaction vessel 39 passes through rest chamber i2 where it is maintained for a periodof time in a relatively quiescent condition to permit further oxidation of lower-oxides oi` nitrogen contained in the gas and the readjustment of the equilibrium between the nitrogen tetroxide and water vapor and II2N205 formed by their combination. If desired, however, the gas from the reaction vessel 33 may he passed directly to reaction vessel '40.

The process for the production of ammonium nitrateas carried out in the apparatus diagram` matically illustrated in Fig. 1 comprises the treatment of a gas containing nitrogen tetroxide,

oxygen and water vapor in two circulatory systems. `In theiirst of these systems, which comprises gas cooler e, reaction vessel il, separator Vand ian, during the circulation of the gas, successive additions of ammonia are admixed therewith in reaction vessel ii to produce amxmonium nitrate which .is separated from the residual gas in separator 25; The heat liberated by `the reaction in vessel il is removed from the circulatory system by dissipation to the surrounding air in the travel of gases from thereaction vessel back to the gas cooler and by contacting'the gases in cooler 4 with the cool dilute nitric acid passing therethrough. The nitrogen tetroxide, oxygen 'and water vapor content of the recirculating gases is adjusted by treatment lwith `the dilute nitric acid and by addition of fresh gases from pipe 3 and the recirculatingv gases then pass to reaction vessel for .admixture therewith of ammonia.

The following conditions are illustrative of one embodiment of my invention, but it is to be understood that the invention is in no wise limited to the conditions specifically set forth.

YA gasirom the heat exchangers of an ammonia oxidation system containing about 9% nitrogen oxides calculated as NO2, about 2 to 4% water yapor and about l to 5% oxygen may betreated in voxidation chamber` 2f. to oxidize the lower oxides of nitrogen to nitrogen'jtetroxide and thence passed at a temperature of,` for example, about 106 C., to gas cooler t where it is cooled to an appropriate temperature by direct contact with dilute nitric acid. Thegas passed into the cooler may be admixed therein with about four timesyits volume of residual gas from pipe 28. The gas leaving thecooler through pipe` l0 Amay contain 'about 5% to 6% NO2. 2 to 4% H2O and l to 5% O2. In reaction vessel it is admixed with about 0.0l'times its volume of substantially pure ammonia gas. The gas leaving `reaction vessel after .separation of the ammonium nitrate in separator 25, is divided and four-fifths may be returned to gas cooler il and the remaini ingone-th passed to gas cooler 3|.

The second circulatory system comprises gas f cooler Si, reaction vessels 3e and 40, rest chamf acid. The gas leaving cooler 3| may be admixed with about 0.004 times its volume ofammonia from pipe 48. Ammonium nitrate is formed and, together withthe residual gas, passes through rest chamber lf2 to reaction vessel' 60. The gas passed to reaction vessel de may have a temperature of about 70 C. and is admixed with about 0.003 times its volume of 'ammonia from pipe 49. Additional ammonium nitrate is formed and the temperature of the gas leaving reaction vessel "|50 rises to about 95 C. The ammonium nitrate produced in reaction vesselsSB and d@ is removed in separator ti l. The residual gas contains about 1% NO2. About four-fifths of the residual gas is recirculated to the gas cooler 3|, while about oneifth is discharged from pipe 4I. A i

In Fig. 3, there is diagrammatically illustrated a process for the production of ammonium nitrate in accordance with this invention in which the nitrogen tetroxide gas is treatedinseries without recirculation of the residual unreacted gases. The apparatus of this figure consists or" `two similar groups, each group comprising a gas cooler |04 or .,ii, a nitric acidscooler |01 or i3d, reaction vessel iii or i559, and separator |25 or |l| which may be of the same type as the corresponding portions ci the apparatus of Fig. l. Although in Fig. 3 an apparatus is'illustrated consisting or" two groups, itis to be understoodthat one or more additicnalxgroups may `loe. employed as may lbe desired. 7.

In employing the apparatus'of Fig. 3, a gas corresponding, for example, to the gas passed togas cooler fi of the apparatusci Fig. l is passed through pipe |03 to a gas cooler |04 where Vit is cooled by direct contact with dilute nitric acid from pipe |05. After contact with the gas the dilute nitric acid is passed through pipe |06 to cooler l where it is cooled by means of cooling water circulated therethrough by way'of pipes iiSand. H39 and returned through pipe |05 to the gas cooler. The cooled nitrogen tetroxide gas con- Vcooler i3! of the succeeding group for treatment in the apparatus of that group for theproduction of additional ammonium nitrate. In gas cooler i3! the residual gasesare cooled and their water vapor content adjusted by direct contact with dilute nitric acid from pipe |32. 'Ihe dilute nitric acid, after contact with the gas, is passed through pipe |33 to cooler |34 where it is cooled by means of cooling water and recirculated through pipe 32 back to gas cooler |3|. The thus treated residual gas passes through pipe |35 toreaction vessel 39 where it is admixed with ammonia from pipe |48. The ammonium nitrate and unreactedl pass through pipegi 38 'tofl'separator I il where theuammoniumi. nitrate;`v is separated 1 out and withdrawn 'through ra pipelllir yThe Aresidual gas is discharged'throu'gh apipe ,llfor 'treatment to recover itsremaining contentof nitrogeng'oxides or disposed of in: any,r desired A'manner..;. V-

The production of Vammonium nitrate; in ac'- V l 1 cordance Withthismodification ofV my invention, j

comprises forming in each lof reactionvessels i l l andliia mixture oi gases containing-,nitrogen itetroxide,foxygenwater'vapor andammonia in 4.5 v Y gen,..tetroxidey Agas :andthe amount'of ammonia'V such proportions that:r the amount of ammonia' .f isilessethan about 033 ztimes the amount required toneutralize allcthe` nitrogen', tetroxide in .the admixture..r .Thenitrogenk oxide gases passed to the reaction vessels are cooledlfingascooler we or; |735 Vto a temperature .which *may be 4about,

`40* C'Lfwhereb'yftthe .temperatureY of. the gases in reaction-'vessels y i I i .anfdr l39-is not increased tok v abovejabout 125 f C; ,by the lneat liberated by the reaction to 'form ammonium.nitrate.l In both Vofithe.gas coolers'the-nitrogentetroxide andv oxygen- VVgasA` is simultaneously vcooled ,and its water Vapor icontent :adjusted byf direct Contact` with aqueous nitricY acid. 3 The above vdescribed `examples of processesfor the production" of ammonium4 nitrate embodying this invention, comprise radmixing :in reaction vesselsizig and wor i li and |39 a-pluralityof successive; additionsjof ammonia with a gasfcon'- taining. nitrogen? tetroxide, fox'ygen' .and 'water vapor. 'The nitrogen'tetroddegas is cooled'` in 'gascoolerslv 3i," it oril .prior vto the intro'- duction oiarnmonia, and rthequantity oieach addition of .ammonia is limited totanamount insuiiicient to"completely.,neutralize'..the nitrogen tetroxideingthe gas with which itis-adrnixed which, Vin the particular processesdescribed, is preferably/between.aboutit.;,and 0.25 times that vreduiredgto `:neutralize allofftheqfnitrogen tetroxideadrnixed therewith. VThe .temperatureof kthe reaction mixture vin each"Y oi'vjessel's i 4;'39, di?,

lil and f i39isf maintained below about 125. C..

by correlating'thedegreefof coolingfof the nitro` ing sense.`

.1. 'In the-processofproducing ammonium ni-l trate by reaction of ammonia-.watervapor,y nit troge'n ,tetroxide and oxygen, that'i'mproyement which comprises forming'. a mixture of said gases nia inisaidmixture isless than about 0.3V times rthe.arnc'iuntrequired to neutralize all'of thehi-` trogen tetroinde therein. j Y

trate byf reaction ofr'ammonia, watervapor, ni-

trogen'tetroxide vand oxygengfthat improvementV A2.. I'n theproce'ssof` produoingfammonium ni*-Y which comprises forming a mixture of-said gases in proportions such that theamount'of Vammonia vinsaid mixture is yless than1abut0'-25 timesrk the kamount required-to fleutraliae'all'of the ni-l f trogen tetroxide'therein. if 1,13.v In the.processofproducingammonium niV v l trate by reaction of ammonia,.watery vapor, nif trogentetroxideand oxygen, that improvement .v said gases throughoutr lbelow about Y125" C.;

cient to heat: the. reaction mix in proportions such that the amount of ammo-v` f' duction of Vammonium Vnitrate hereinbefore described;Y f

v,which comprises :maintaining thetemperature "of the course `of the reaction '4. In the process of producingiammonium ni; Y

trateby reactionof ammonia, water vapor, nif trogen tetroxid'e` and'oxygen, thatlimprovement which., comprises mixing `said Vgases and`V main,- f

'taining 'theV temperature of'. saidV mixed `gases throughout the course ofr the reaction below .about .125 C1 and above the dew point oi the Vwater vapor in said mixture; 1

trogenftetroxide andoxygen, that improvement y .which'comprises,maintaining said gases throughout the course of the reaction at temperatures be-V tween about 40? C. to 125 C. Y l.

f6. The process/of producing ammonium nitrate t whiciigcomprises admixing ammonia with a gas,

containing nitrogen tetroxide, oxygen and water t Vapor',jiimiting the quantity of said ammonia to an amountinsuicient. to neutralize all the ni trogen tetroxide contained in'said gas, and main-- taining'said mixture throughout` the course of the 4' reaction at a temperature below 'about 125 C.

f '7. The 'processoi producing ammonium nitrate which comprisesadmixing ammonia withV a gas containingnitrogentetroxide, oxygen and water vapor, limiting thequantity'of said ammonia to an amount insufficient to neutralize" all the nitrogen 'tetroxide v contained in saidA gas, and

1 maintaining said`inixture throughout the ciiurse lof; the reaction'at'a'/ temperature above' the dew 'pointV of the water va'por in the mixture and below about12r5 C* Y t Y Y 8. The process jf producing 'ammonium nitrate which comprises admiring ammonia witha gras containing'ntrog'en rtetroxide, Yoxygen and water vapor and limitingfthe quantity yofthe ammonia to ran amount such that the heatliberated by `:5..In the process v,ofproducing ammonium yni-f t Vtrate. by reaction i-ammonia, water vapor, ni-

reaction of the'v ammonialwith said gas is insumtureabovevabut `125" C. l Y n 9; Theprocess of producing' ammonium nitrate which `comprises introducing ammonia into a t cooled'gas mixture containing nitrogen tetroxide,

oxygen and water vapor and correlating thetemperature to.v whichsaid mixture istcooled and the reaction offsaidammonia with' the gas'mixture.

10. The process Vof producingY ammonium nia cooled gasv mixture containing nitrogen tetroxide, ycnrygenxjan'd water vaporyrcorrelating theV ,temperature to whichjsaid mixture is j cooled and the quantity of ammonia added thereto whereby Athe reaction mixture is heated to a temperature belowf about 125 C,y by the heat' liberated by reaction of said ammonia with the gas mixture, separating vammoniiun nitrate .thus produced fro'rn'the residual gas; cooling the Wresidual gas fand adjusting its contentfor" lnitrogen tetroxide,

oxygen'gand Wateri vapor to produceiajgas mixture` having-substantially the same composition fasthe laforesaid cooled gas mixture andemploying ,the resulting cooled gas mixtureriorthe proinv Y the. manner 11; The process of producing ammonium` nia gas mixture containing nitrogen tetroxide, oxygen 'andwater vaportat atemperature of labout 40 C., limiting rthe quantity of fthe ammonia' to turej to Ya tempera'f.

, quantity offam'monia added thereto whereby the i reaction" mixtureV is heated toV r,a temperature below about 125? C; gby Vthefhrzfat liberated byA .t trate twhich comprises introducing ammonia rinto ytrate which comprises introducing ammonia into temperature above about 125 C., separating ammonium nitrate thus produced from the residual gas, adjusting the content of nitrogen tetroxide, oxygen and water vapor of theresidual gas and removing heat therefrom to produce a gas mixture having substantially the same composition and temperature as the rstmentioned gas mixture, and employing the resulting gas mixture for the production of ammonium nitrate in the manner hereinbefore described.

I 12. lIn the processor producing ammonium nitrate by reaction of ammonia, water vapor, nitro- `Ygen tetroxide and oxygen,V that improvement v which comprises cooling agas containing nitrogen tetroxide-by directly contacting said gas with an aqueous nitric acid solution and mixing enmonia with the thus` cooled gas.

i 13. In the process of `producing ammonium nitrate by'reaction of ammonia, water vapor, nitroigen tetroxdel and oxygen, that improvement `which comprises cooling a gas containing nitrogen tetroxide by directly contacting said gas with an aqueous medium and mixing ammoniawith the." thus cooled gas.` i i 14. In the process ofproducing ammoniumV nitrate by reaction ofY ammonia, water vapor, nitrogen tetroxide and oxygen, that improvement Vwhich comprises simultaneously cooling and adjusting the water vaporV content of a gas conf taining nitrogen tetroxide and oxygen by directly contactingsaid gas with an aqueous nitric acid A solution having a predetermined composition and temperature and mixing Yammonia with the thus cooled gas.

` 15. The process oproducing ammonium nitrate which comprises simultaneously cooling and adjusting the water vapor content of agas containing oxygen andl not more than about'6.5% nitrogen'tetroxide by directly contacting said Vgas with about 50% aqueous nitricacid solution at a temperature of about 40 C.,'and introducing ammonia into the'thus cooled gas.

16. The process of producing ammonium nitrate which comprises simultaneously cooling and .adjusting the water vapor content oifa gas containing nitrogen tetroxide and oxygen by directly contacting said gas with an aqueous nitricacid solution having a predetermined composition ,and temperature, introducing ammonia into the thus ,cooled gas in amount insu-Iicientto completelyA Vneutralize all of the nitrogen tetroxide therein to Aform ammonium nitrate, separating the residual gas and ammonium nitrate thus produced, introducing into the residual gas nitrogen tetroxide and oxygen, cooling and adjusting the water vapor content of this gasby directly contacting itA with aqueous nitric acid to produce a gas mixture having substantially the same composition and temperature asV the aforesaid cooled gas, and employing the resulting cooled gas mixture for the production of ammonium nitrate in` the manner hereinbefore described.A

17. The process of producing ammonium nitrate whichcomprises introducing successive additions of ammonia into a gas containing nitrogen tetroxide, oxygenV and water vapor, limiting the quantity of each laddition of ammonia to an amount less than aboutY 0.3 times that required to completely neutralizeall of the nitrogen tetroxide in the gas into which said addition is introduced, separating ammonium nitrate formed to completely neutralize all of the nitrogen tetroxide in the gas into which said addition is introduced, separating ammonium nitrate formed from the residual gas, cooling the gas prior to addition of ammonia thereto to about 40 C., and maintaining the temperature of the reaction mixture formed by each of said additions of ammonia between about 40 C. and 125 C.

19.111 the process of producing ammonium nitrate by `reaction in the gaseous phase of ammonia, water, nitrogen tetroxide and oxygen, that improvement which comprises reacting on said nitrogen tetroxide, oxygen and water vapor with ammonia in a plurality of stages and limiting the quantity `of ammonia available for reaction with the nitrogen tetroxide ineach stage to not more than about 0.3 times the amount required to neutralize all of said nitrogen tetroxide in each stage to form ammonium nitrate. v

20. In the process of producing ammonium nitrate by reaction in the gaseous phase of ammonia, water, nitrogen tetroxide and oxygen, that improvement which comprises reacting on said nitrogen tetroxide, oxygen and water vapor with ammonia in a plurality of stages, and limiting the quantity of ammonia available for reaction with the nitrogen tetroxide in each stage to less than about 0.25 times the amount required to neutralize all of said nitrogen tetroxide in each stage to form ammonium nitrate.

2l. The process for the production of ammonium nitrate which comprises circulating a gas containing nitrogen tetroxide, oxygen and Water vapor in a circulatory system and during the circulation of said gas admixing therewith ammonia whereby ammonium nitrate is produced, limiting the quantity of said ammonia to an amount less than about 0.3 times that required to neutralize all the nitrogen tetroxide in the reaction l mixture, separating ammonium nitrate thus pro- `duced from the residual gas, removing from the circulatory system heat liberated by thereaction, and adjusting the nitrogen tetroxide, oxygen and Water vapor content of the recirculating gas prior to admixing ammonia therewith.

22. The process for the production of ammonium nitrate which comprises circulating a gas containing nitrogen tetroxide, oxygen and water vapor in a circulatory system and during 'the circulation of said gas admixing therewith ammonia whereby ammonium nitrate is produced, limiting the quantity of said ammonia to an amount less than about 0.3 times .that required to neutralize all the nitrogen tetroxide in the reaction mixture, separating ammonium nitrate thus produced from the residual gas, bleeding from the circulatory system a portion of the gas therein, admittingto said system additional quantities ofY gas containing nitrogen tetroxide and oxygen, Ycooling the circulating gas and adjusting its content of waterl vapor-prior to admixing the ammonia therewith and so correlating the aforesaid steps of the process as to maintain substantially lmists-ua the conditions 'un ,der i which, each sp' of the process operates. ,Y

: 23. The A processy fortlie' .production .of ammonium nitrate wiiicli comprises circulating a, gas

rcontaining nitrogen tetroxide, oxygen ,and L'Water Vapor inajcirculatory systemandduringv the cirjculation of said gas admixingitlicrewith aminoniawhereby'anunoniumnitrate is produced, lirniting the quantityof said ammonia` tojan amount less than aboutgotinies.thatjrequired to neu- ,tralizefall'tne nitrogenltetroxide in the reaction 'mixture Yseparating. ammoniumrv nitrate thuspiol (duced from thefresidual gas,l bleeding'froinxthe circulatory system aportionof the gasl therein, adnn'tting to-said systemv auditienal quantities ifo ,s v.gas containing 'nitrogen tetroxide and oxygen,

cooling the circulating Ygas, and adjusting itscon-v tent; ci ,water Vapor prior to adinixing thefainf monia'tlierewitli ,e by direc lyl contacting said Ygas d'prior tog'.

withv an aqueous solution of Ynitric aci admixing tlie ammonia, therewith,v and maintaining the temperaturegof the reaction mixture v Y Y of ammonia andsaid circulating. gas below about f 24. The vprocess, for the production ofi-'ammonium nitrate` which comprises ,circulating a gas containing nitrogen tetroxide, oxygen and water vapor in a circulatory system and during the ciroula'tion'of said gas adrnixing' therewith ammonia wherebyarnmonium :nitratev is produced limiting v the quantity ,of said ammonia to anamountbe-z tweenabout 0.1 'andfztirncs'that required to i neutralize lfall the nitmgenV tetroxide in the. reacucirculator system al portion` loi the gases therein,v admitting to4 said lsystem additional quantities oi gas containing. nitrogen tetroxideand oxygen,- cooling'tlie circulating v'gask and adjusting its "c'on- .e o %fnitric acid at a'temperature of about do" 16.1,@ and maintainingthe Ytemperatureof the reaction t mixture,Vv separating ammonium nitrate Vthus produced from tlie residual vgas,.bleeding fronitlie tent oiiwater vapor by directly contactinglit with an aqueous solution' of, nitric acid containing about l tionrnixture of ammonia and-said coolcdgas below about 125 C;

nitrogentetroxide in ,the gas admiXed therewith;

5-5 Vl trate which comprises gadm'ixing i successive Vadditions oiammonia with a gas containing nitrogen tetroside,` oxygen/and. water vapor, limitingtlie quantity of' eachladdition of ammoniaito anvr f 66 amount Vless than about 0,25 times that required 65"' trate whicli comprises-admiring successive addiv tionsof'ammoniawith sigas-containing nitrogen '1 and maintaining the temperature of the reaction mixturebelow alooutflZio C.-A v v ,f 26. .The 'process' of `producing fammoniinnl m'- to completely neutralize-fthe nitrogen tetroxide in the gas admixed therewithgfand maintaining the temperatureoi the reaction mixture below about* Y, "tetroxide, oxygen and watervapor, limitingthe quantity oi each addition vofV Vammonia-to; an

amount insuiiicient to ceinpletelyneutralize the'- Y 4nitrogen tetroXide inthe gas admiredr therewith, y maintaining the` temperature of? the'reaction rmixturejbelc'lw about 125Q'C. and intermediate f theintroductionv of twofoi said additionsof'amyrrionia maintaining-the gasV containing ammonium "nitrate fora periodici timein relativelyV 27"11'19 process Of producing ammonium. nir .which rcomprises( admixing ammonia Iin 'a plu- "quiescent condition. Y

I `28'. They process for the production of ammoj nium `-nitratewliicli 'comprises recir'c'ul'ating a gas- Y containing nitrogen'tetroxide,oxygenandlwater vapor in a circulatorysystemV and during the-cir- I Youlationl of saidl gas admixingtherewith successiveadditons of ammoniaftoproduce ammonium vture and watenvapor content of the circulating gas prior'to the addition tlieretoof ammonia, .continuously Ywithdrawing'fr0-in the aforesaid circulatory system a' portion of the gas' circulating therein,v passing the withdrawngasinto a'second'circulatory system wherein it is recirculated and during its circulation in said secondV system I mixing said gas with successive additions of ammonia toproduce additional ammonium-nitrate,

separating the residual gas and Yainxnoniurn nitratetlius produced, adding to `the residual gas nitrate, separating the Yresidual gaszand A'ainmothe gaswithdrawn fromth'e iirst mentioned ciri culatoryfv system'and adjusting thev temperature and ,water Vapor;y content of tne'circulating gas, landin both of the aforesaid, circulating systems n limiting the amount of eachoi saidfadditions ofY ammoniaadmiiied thecirculating gasto not more thanuil timesr thatrequiredV to neutralize all the-nitrogen tetroxide `present inthe reaction mixture and maintaining the reaction mixture at temperature below about 1725970.` v y 29. yThe-process for tlie production'fo'i ammoniurnr nitrate which comprises recirculating a gas 'containing nitrogen tetroxidaoxygen and Water vapor in acirculatorysysternand"during-the circulation of said gas admixing Vtherewith succeslsive additions of y,ammonia to produce ammonium vnitrate,ttrnaintaini ng the reaction mixture at a temperature,belowabout 125 separatingrthe r residual,gas and ammonium nitratefadding to ther residual `gas nitrogen tetroxide and oxygen, adjusting` thetemperaturefand water Vapor conv tent of the Acirculating gas rI'Jriorvatotne addition V'thereto;'orammo-nia, by directlycontacting said g-a's withl an aqueous solution o f nitric acid at a temperature of abonnees; o., continuously witn- "drawingffrornthe aforesaid circulatory system a iportionjof the, gas circulating therein, passing the withdrawn gas ntoa second Vcirculatory system wherein it is circulated and during itscirculation said second system mixing said-gas with` successive additions of ammonia toproducev ad- Yditional ammonium nitrate,`niaintaining. the re- Y i A`actionmixture,,at a temperaturel below about iC.,1-separating the residual gas andammonium nitrate thus produced, adding vto the residual gas, the jgas Withdrawn fromthe first men- Y tioned circulatory systemga'nd adjusting thek temperatureand rwater vapor content :of tlie, circulating gas byA directly contacting'said gas withv an aqueous solution oinitric acidat a temperature k.lofaloout40j C.v Y

Si).y The' process ofp'rodu f U ammonium' nitrate 'Y' tetroaide, water Vapor 'and a'quantity4 of oxygen not'greatertlianraoout 10%,of the tota-l'volume v of :sai-dm.gas',V liiniting'tlie quantity of ammonia lavailablefor reactionwith/tlie nitrogen tetr-oX- ide ineacli stage VVto V:not more than about 0.3 timesk kthev amount'reduired lto neutralize all of said nitrogenitetroxide'tcfiorm ammonium nitrate, and V*maintaining the reaction-mixturein each 'of saidl stages'at a temperaturefbelowabout i25fC; U A

. 5F31. The'fprocess fori the f'production 'of ammoniun'fi nitrate` which comprises mixingV ammonia with Va 'gas'containing nitrogen tetroxide,lloxygen{ 'the proportions of less than 0.3 parts of ammonia,

1 part 'of nitrogen tetroxide, and from 0.5 to 2.5

- parts ofiwater vapor. f

-*L33.`-The process for the production .of ammonium nitrate which! comprises mixing. ammonia,

nitrogen tetroxide; oxygen: and vlivater Vapor'. in the .proportions .'of. not more than'aboutiparts of ammoniagabout `l part ofnitrogen tetroxide and between about 0.5and 2.5 parts of Water vapor and maintaining the temperature oflthe Y additions of ammonia-below about. 125? C.

reacting Vgases between about. 40 C.` and 125 C. 34.. The process of producing ammonium nitrate whichy comprises introducing successive additions of ammoniainto a gas containing.nitrogenxtetroxide,.oxygen and Water vapor, said gasxcontaining. about 0.5toy 2.5 parts of `Water vapor. to .every .1

part of nitrogen tetroxide, limiting the quantity vof` each addition. of'` ammonia toan amount less than about 0.25v times' thatlrequired tocompletely. neutralize .all of thenitrogen tetroxidev in thegas into which said addition is intro-duced, separating ammoniumnitrate `formedfrom the residual gas,v cooling thegas prior tolthe addition of ammoniathereto by directly contacting it with an aqueous nitric; acid solution at a vtemperaturegof about 40, C., and maintaining thatemperature ofy thewreaction mixture formed by `each vof said *85. The processjoi producing ammonium nitrate which comprises introducing a concentratedammonia gas into amixture of, nitrogenoxides,

oxygenand water vaporiin which .80% or more of the nitrogen oxides `are present as nitrogen tetroxide and limiting the quantity of ammonia to not more than 0.3 times the amount required to neutralize all of the nitrogen tetroxide to form ammonium nitrate. Y Y Y 36. The process of 'producing ammonium nitrate Which comprises introducing a concentrated ammonia gas into aA mixture containing nitrogen tetroxide, oxygen and Water vapor, limiting the quantity of ammonia added to an amount insufficient to neutralize all thenitrogen tetroxide conf tained in said'gas mixture to form ammonium nitrate, and maintaining said mixture throughout the course of the reaction at a temperature below about 125 C.

37. The process for the production of ammonium nitrate Which comprises recirculating a gas containing nitrogen oxides, oxygen and Water vapor in a circulatory system, introducing a concentrated ammonia gas into the circulating gases in amount less than about 0.25 times that required to neutralize all of the nitrogen tetroxide in the gas admixed therewith, maintaining the temperature of the reaction mixture below about 125 C., separating from the residual gas the ammonium nitrate thus formed, and prior to recir- V culation of the residual gas for introduction thereinto of ammonia, replacing the nitrogen oxides and oxygen removed from the gas in the formationiofV ammonium nitrate, and cooling the gas to a temperature. of about 409 i C. and adjusting therwater vapor content by directcontact of said' gas vWith aqueous nitric acid. A l' 1 v38; The process of producing ammoniumnitrate which comprises introducing 'ammonia' into a gas containing oxygen, Water vapor andnot more than about"l6%' nitrogen tetroxide and limiting the quantityof ammoniato` an amount less than` about 0.25 .times that required to neutralizeall thenitro'gen tetroxide toform ammonium nitrate. 39. iThe process of producing ammonium nitrate which `comprises` passing a ,gas containing not more than .about 6.5% nitrogen tetroxide, and oxygen into direct contactwith an aqueous solutionsof nitric acid containing about I-INOs at about 40 C,-,Jintroducing ammonia intorthe thus treatedgas in amount' insufficient tov neutralize allV the nitrogen tetroxide contained thereinfto 'Y form ammonium nitrate, and maintaining the reacting mixture of'igases Vat atemperature below al:noui',125.";C.n .j 1 l. v

V14,0."Ihe process of producing ammonium nitrate which comprises .passinga gas containing not morefthan'about 6% nitrogen'tetroxideand oxygen into direct .contact with an 'aqueous solution of nitric acidcontainingabout 50% `I-INOa at'.

about 40 C., introducingammoniainto the thus i treated gas in amountflessA than about 0.25times that. required/to neutralize. all `the l nitrogen tetroxide contained therein, maintaining` the. reactingfrnixturerof gases at atemperature below; about "125".` C.,.separating the ammonium nitrate thus Aformedfrorn theresidual gases; and reacting the .residual gasiwith .an `additional quantity of ammoniaunder substantiallythesame condi-` tions as; hereinbeforev describedgfor the rst -mentionedl gas 'containing nitrogen tetroxide and oxygen., i '41.1'Intthe processyof producing ammonium nitrate-.by reaction in the `gaseousphase of am-` monia, Water, nitrogen tetroxide and oxygen, vthat improvement `Which comprises introducing arnmonia into a'stream of gas containingnitrogen tetroxide, -oxygen and. Water vapor` `While lmechanicallyimparting a turbulence to. said stream of gas.

42. In the process of producingv ammonium nitrate by reaction in the gaseous phase of ammonia, Water, nitrogen tetroxide and oxygen, that improvement .which comprises introducing a restricted flowing stream of concentrated ammonia gas into a flowing stream of gas containing nitrogen tetroxide, oxygen and Water vaporV While mechanically imparting a turbulence to said last mentioned stream of gas.

43.-In the process of producing ammonium nitrate by. reaction in the gaseous phase of ammonia, Water, nitrogen tetroxide and oxygen,

, that improvement which comprises introducing a stream of concentrated ammonia gas flowing at high velocity into a `stream of gas containing nitrogen tetroxide, oxygen and water Vapor While mechanically imparting a turbulence to said last mentioned stream of gas.

44. The process of producing ammonium nitrate which comprises preparing a mixture of nitrogen tetroxide, oxygen and water vapor having a temperature of vabout 40 C., introducing ammonia into a turbulent stream of said gas, limiting the quantity of ammonia thus introduced to an amount not greater than about 0.3 times the amount required to neutralize all of the nitrogen tetroxide, and maintaining the temperature of the reacting mixture of gases below about 125 C.

y y vapor'ifin'a'circulatory systemand 'insaidsystem' "nitrate whichf=comprises icirculatingja gasirconi-rv taining nitrogen tetrOXidi Oxygen-,fand water introducingM arconcentrated: ammoniaifgas into AaY turbulent stream of'said gasinlamount less than Y into the J residualzgas f iniamount 'fsuch that :the

` resulting, gas mixture` containsg notzgmoregthan f aboutjf`6% :nitrogenftetroxide vand.' directly con-v s temperaturet about 4D?. C'. prior tofthe introduce tion thereto of 'ammoniagasfas shereinlnefore"y tacting saidgas'mixturewitlisan' aqueous solutionr described.

20': nitrate Whichqcompris'es circulating agas con.

taining nitrogen ',tetroxide, f oxygen and ',Wate'r. vaporin acirculatorysystem anduinisaid system introducing-arconcentrated ammonia gas into a turbulent stream ofi' said" gasfirrfamount between separatingzammonium irn'tratefY thus vrformed from ,s

1 l theresidual gases; removingrffrom'; the `system-,- a portionA of ,the residualgas; introducingV *nitrogenA 303y tetroxid'e and :oxygen into the'jresiduaJ-gas fre- 't mainingfri said" system,'1in amount/suoli that the' f" resulting"gas:mixture contains'about-5%"`to 6%,

nitrogen tetroxide;l Ydirectly f'contac'ting said .gas mixture lwith" an'a'queous solutionerof nitric; Aacidl' :containingv about v510% HNOsqatjV atemperature of i kabout 40 prior `tothefintrduction thereto famxnoniajgasas herein'before describedgntro,-V ducingtheresidual gas removed from the faforef;

i Said. circulatory system yinto asecond rcirculatory 1 01 (system,` mixing Isaidgaswitllraf ga'svcontainingf culated-therein, t directly contacting thesamixed i gases- Witl'anaqueousrsolution of` nitric acid con-vr tainingabou'ta50Zg` .I-INOs at a-temperatureiof l 'about' 40 .i Cgi!! introducing alzconcentrat'ed i .am-

gases,"introducing nitrogen tetroxide and oxygen:

fv nitric acidv vcontaining"about C50%;I-INOi -at a Y Y and'water Vvapor remainin'gzin said system Ywith the'gas Withdrawn from the rst mentioned cirprocessY 'of producing` fs'ammoniumf from'aV gas 'in whichit issus'pended all connected .byoonduits for circulation'ofgas therethrough,

aorn'zofri t y v fzfnonia'iglis into aturbulent stream of the thus treatedmixed gas in'amount between about 0.1 and O.25timesfthefamount required to neutralize allfofpthenitrogen tetroxide inthe gas,r maintaining the thus treated gas fora period of time in a i5 relativelyquiscentcondition, lintroducing a `iurther yquantity of, a ,concentrated ammonia gas into `al;turbul'er'rt: streamofV the/thus treated gas f inA amount between about A0.1 and 0.25 times-the amount Tequiredto neutralize all of the nitrogen tetroxide t in the gas, separating A,the ammonium nitrate 'thus vformed Vfrom the` residual rgas', With-` drawing; from the second Vcirculatory system a ,portion-fof V'saidfresidualz gas, and mixingy the ref S'dual -gas containing nitrogen "tetroxide, oxygen culatory system as hereinbefore described.

`v`"147An apr'naratus:fon/thev production ofY ammoniungfnitra'te; by"y vreactonzof ammonia, lWater y Vapor, ,el nitrogen tetroxidel and Y oxygen, compris-` i ing/a ,losedcoirculatory system, saidsyst'em comprising .in Y'combinationv agas cooler, a reac-` tionyessel :and a"separator.for removing :a solid meansfor .introducing gaseousreactants into said` ks5VIstern',`fsaid,means comprisingmeansfor introducing Y, into.. said. reaction' vessel at' least vone* of the gaseous..lreactantsjseparate from the others,

' means'orsrecirculating: gasintroduced'into the system .fin Vseries-.through saidV coolenreaction vessel and separating means; and asecond closed circulatorysystem' comprising'incombination a gas 'coolenia vreaction Vessel and a separator Yfor rremoving(alsolid from a gas irrwhichY it is suspended meansfor'withdrawing a porton'of the gasfcirculatingS in the lrst v'merltone'd circulatory system and: introducing it pintoV vthe" .second circulatory .Is5.fstem,- means forvintroducing gas into 40 the lastifmentione'd reactifvnr,-r Vessel, and means rforrecirculatirig'gas introducedl into said second systernf-inY seriesy throughA the' cooler, reaction t `vessel and `separator offsaidsyste Y' HERMANALBERT BEEKHU'IsgJR. 5 

